Discharge printing of textiles



Patented June 22, 1943 DISCHARGE PRINTING OF TEXTILES George W, Seymourand George C. Ward, 7 Cumberland, Md., assignors to Celanese Corporationof America. a corporation ware of Dela-r No Drawing. Application March29, 1941, I

Serial No. 385,852

I 6 Claims. This invention relates to an improvement in the dischargeprinting of textile materials and I relates more particularly totheformulation of printing pastes used in the discharg printing of fabricsdyed in dark shades with azo dyes so that more desirable illuminateddischarge patterns may be obtained.

An object of our invention is the preparation of discharge printingpastes and the discharge for solubilizing the leuco vat dye and permitit to penetrate the fabric, a reducing agent for the dyes used both forthe ground colorand as the illuminant, generally a sulfoxylate formaldhyde such as sodium or potassium sulfoxylate formaldehyde and whenorganic derivative of cellulose fabrics are treated, also preferablycontains a swelling agent to permit better penetration of the fabric bythe reducingagenha thickener to keep the paste from spreading orcreepprinting, with said pastes, of fabrics dyed in dark 1 ing andenough water to make a thick paste. Ilshades with azo dyes to obtainclear, bright and luminated discharge prints obtained on dark azosharpilluminated discharge pattems. dyed backgrounds by using discharge"pastes con- Another object of our invention is the prepara- 'taining theabove mentioned alkalis for solubiliz tion of discharge printing pastesand the pro,- ing the vat dyestuffs were frequently unsatisfacduction ofclear, bright and sharp illuminated l tory, however, since'the colorvalue of the disdischarge Dattems free of mottled effects. chargepattern obtained was poor, due to un- Other objects of our inventionwill appear from even penetration. This resulted in the presence thefollowing detailed description. of a halo of partially undischargedbackground The discharge printing of textile materials is color aboutthe edges of the illuminated discharge widely used in the dyeing art forobtaining patpattern, and a mottled appearance in the print. Y terneffects on fabrics in a simple and economic We'have now discovered thatif salts of an manner. Generally, the fabric which is to be acid ofphosphorus having abasic reaction are printed is dyed in the piece in asolid color by incorporated in discharge printing pastes conmeans of asuitable dyestui'f to provide the color taining vat dyes tosolubilizesaiddyes, instead desired as th background. When the fabric isof the alkaline compounds heretofore incorpodyed with an azo dyestufl',a chemically active ratcd therein, improved results are secured.- Thedischarge paste, having a reducing action on illuminated dischargepatterns obtained by using the azo dye forming the background color, isthese pastes ,are clear, bright and sharp, are unapplied to the fabricin a predetermined pattern mottled, and the objectionable halo aboutthe. and the fabric then treatedso that the azo dye edges of thedischarge pattern is no longer obis reduced and split at the diazo groupand the tained. background color is removedat the points where The saltsof the acids of phosphorus which the paste has been applied, yielding awhite patmay be added to the discharge, printing pastes to ternor'design upon a colored background, When solubilize the vat dyes arethose whichare basic ltis desired to obtaina pattern or design in colorin reaction and may be, for example,alkali metal instead of white, thatis, an illuminated discharge salts of the phosphoric and phosphorusacids print, it is preferable to apply, simultaneously such as secondaryand tertiary sodium orthowith the destruction of the ground color, adyephosphate, and secondary and tertiary potassium stuff which is eitherresistant to reduction and is orthophcsphate. While these phosphates areall itself adye for the fabric or one which can be 40 suitable, wepreferably employ tertiary sodium reversibly oxidized after being vattedto the leu'co orthophosphate. form. In general, it is the vat dyestuffswhich As a ground color, any suitable azo dyestuif .may be used forillumination sinc these dye-- may be used. Our invention is particularlyof stuffs are capable of being reversibly oxidized importance inconnection'with the illuminated after being vatted. The vat dyestuffsmay be discharge printing of fabrics which have been applied to thefabric mixed in with the discharge dyed with azo dyes which uponreduction by the paste and the method of application of the pastedischargeagent form products which are reasonis similar to that wherewhite discharges are obably soluble in water.

tained. The discharge paste may be locally applied to The dischargepastes heretofore employed in the fabric by any suitable means such asprintconnection with a'zo-dyed fabrics for obtaining ing with embossedor engraved rollers, by stencililluminated discharge patterns usuallycomprised line or with'blocks. a vat dyestufl for the print color, analkali such After the discharge paste i applied t th as sodium or'potassium hydroxide or carbonate fabric by any one ofthe above methodsor their equivalent, the fabric is then dried and aged in are given:

a suitable ager so that the background color will be acted upon by thereducing agent in the paste and the color destroyed. The continuous ageror cottage ager may be used and the ageing is generally carried out atabout 98 C. to 101 C. for a period of time sufficient to discharge theazo dye. This period may be from about to 20 minutes depending on thetype of fabric and the particular dyestufl's used. The fabric is thenwashed to remove the decomposition products as completely as possibleand to wash out the alkali metal phosphate so that the insoluble leucovat is precipitated. The dye may then be oxidized from the leuco form byexposure to air or by an oxidizing bath. After a final wash with waterthe fabric is dried.

While our invention is applicable to the treatment of azo dyed textilematerials generally, it is of particular importance with respect tofabrics or other textile material made of or containing yarns or.filaments of an organic derivatiue'of cellulose. As examples of-suchderivatives there may be mentioned cellulose esters, for example,cellulose acetate, cellulose propionate, cellulose butyrate, mixedesters such as cellulose acetate-propionate and celluloseacetate-butyrate, and cellulose thers, for example, ethyl cellulose andbenzyl cellulose. Mixed materials containing one or more of theaforementioned cellulose derivatives together with other textile fibersmay likewise be treated in accordance with our invention. Such materialsmay contain, for

instance, in addition to a cellulose ester or ether, cotton, wool, silkor a regenerated cellulose type of artificial silk.- i

In order to illustrate our invention but without being limited theretothe following examples Example I A cellulose acetate fabric dyed with 4%or 4'-nitro-benzine-azo-2-amino-4- acetylamino anisole is diazotized andcoupled on the fabric with 4% of meta-di-hydroxyethyl-amino-aceiianilideand then topped with 0.5% of p-nitrobenzene-azodioxyalkyl-m-toluidine,which topping yields a fabric of deep brown shade. The fabric is thenprinted with a discharge paste made up as follows:

Parts by weight Indanthrene Golden Yellow GK (Schultz Farb- The printedfabric is then dried and aged in the rapid ager for 13 minutes at 99 C.to reduce the azo ground color. Thereduction products are removed andthe leuco vat dye precipitated by washing the fabric in an aqueoussolution containing 2 grams per liter of sodium hydroxide. 'The fabricis then worked for 2 minutes in a bath containing 5 grams per liter ofsodium perborateand 2 grams per liter of soap maintained at 50 C.,thereby oxidizing the leuco vat dye in the discharge pattern. After athorough rinsing in clear, cold water the fabric is dried and theresulting fabric has an apple green figure on a dark brown background. IThe printed pattem is distinguished for its sharpness, clearness andexcellent color value, and for its freedom from any halo about the edgesof the green figure.

Humnple ll A mixed cellulose acetate/viscose 'rayon fabric is dyed byknown methods to a solid, dark brown shade with a dye compositioncomprising the.

Fastusol Yellow LRA (Color Index 349-41) 1.0

After being dyed, the fabric is then printed with a discharge paste madeup' as follows:

Parts by weight Sodium sulfoxylate formaldehyde 10 Sodium thiocyanate 20Supertex gum Water i 7 Sodium benzyl sulfanilate 3 Tertiary sodiumorthophosphate 5 Indanthrene Golden Yellow GK 10 The printed fabric isthen dried and aged in the rapid ager for 15 minutes at 99 C. to reducethe ground color. The fabric is then washed and the leuco vat oxidizedas described in Exampie I. The resulting fabric has a-yellow figure on'adark brown background and the printed pattern is sharp, clear and freeof halo about the edges of the yellow figure.

It is to be understood that the foregoing detailed description is givenmerely by way of 11- lustration and that many variations may be madetherein without departing from the spirit of our invention.

Having described our invention, what we desire to secure by LettersPatent is:

1. Process for the production of illuminated discharge efiects-on an azodyed textile material, which comprises locally applying to said dyedmaterial a reducing discharge paste comprising a vat dyestuif and a saltof an acid of phosphorus having a basic reaction, subjecting the treatedmaterial to ageing, whereby said azo dye is decomposed by means ofsald'paste, removing the decomposition products of said discharged azodyestufi and subjecting said material to oxidation to illuminate theportions of the material printed with the vat dye.

2. Process for the production of illuminated discharge effects on an azodyed textile material 2 containing yarns of an organic derivative ofcellulose, which comprises locally applying to said dyed material areducing discharge paste comprising a vat dyestuff and a salt of an acidof phosphorushaving a basic reaction, subjecting the treated material toageing, whereby said azo dye is decomposed by means of said paste,removing the decomposition products of said discharged azo dyestuif andsubjecting said material to oxidation to illuminate the portions of thematerial printed with the vat dye.

3. Process for the production of illuminated discharge effects on an azodyed textile material containing yarns of cellulose acetate, whichcomprises locally applying to said dyed material a reducing dischargepaste comprising a vat dyestuff and a salt .of an acid of phosphorushaving a basic reaction, subjecting the treated material to ageing,whereby said azo dye is decomposed by means of said paste, removing thedecomposition products of said discharged azo dyestufl and subjectingsaid material to oxidation to '11- luminate the portions of the materialprinted with the vat dye.

4. Process for the production of illuminated discharge effects on an azodyed textile material containing yarns of cellulose acetate, whichcomprises printing said dyed material in a predetermined pattern with.areduciiig discharge paste containing a vet dyestufl! and an alkalimetal salt or an acid of phosphorus having a basic reaction, subjectingthe printed material to ageing so as to decompose said azo dyestufl bymeans of said discharge paste, washing said I rial containing yarns ofcellulose acetate,

determined pattern with a reducing discharge paste containing a. vatdyestuil and tertiary sodium orthophosphate, subjecting theprintedmaterial to ageing so as to decompose said azo .dyestuff by meansoi said discharge paste,

material to ageing so as to decompose said azo textile material toremove decomposition prod- .ucts of said discharged azo dyestufl. andsubjecting said material to oxidation to illuminate the portions printedwith the vat dyestufi.

5.-Process for the production of illuminated discharge effects on an azodyed textile material containing yarns'ot cellulose acetate, whichcomprises printing said dyed material in a predyestufl by means of saiddischarge paste, washing said textile material toremove decompositionproducts or said discharged azo dyestuii! andsub- .iecting said materialto oxidation to illuminate the portions printed with the 'vat dyestufl.

GEORGE W. SEYMOUR. GEORGE C. WARD.

washing said textile material to remove decomposition

